1. Field of the Invention
The present invention relates generally to a radio communication terminal, and more particularly to an antenna of a radio communication terminal that can receive and transmit a call communication signal but also receive a television (TV) broadcasting signal.
2. Description of the Related Art
Generally, with the rapid development of networks for providing information, the development of a composite radio communication terminal having diverse functions in addition to the audio transferring function has been required. Accordingly, a composite radio communication terminal containing a portable terminal for viewing TV in addition to the audio transmitting/receiving function (hereinafter referred to as a TV phone) has been developed. An example of such a TV phone is contained in a Korean Patent Application bearing application number 1999-31824, entitled xe2x80x9cInformation Display Method in a TV Phonexe2x80x9d, and filed by the applicant herein.
Since the TV phone needs to receive a TV broadcasting signal as well as being capable of the transmission/reception of an audio signal, a problem is created in designing an antenna and associated circuitry for receiving both types of signals.
FIG. 1 is a block diagram illustrating an antenna structure of a conventional TV phone for receiving an audio call signal and a TV broadcasting signal. Referring to FIG. 1, the TV phone 10 includes an antenna ANT_T for receiving the TV broadcasting signal, and an antenna ANT_P for transmitting and receiving a code division multiple access (CDMA) audio signal used in a typical digital portable phone. The antenna ANT_T for receiving the TV broadcasting signal is connected to a TV tuner 12 in the TV phone 10, and the antenna ANT_P for transmitting and receiving the audio signal is connected to a phone duplexer 14 in the TV phone 10. Though having the respective antennas for the audio signal and the TV broadcast signal achieves good receiving sensitivity for the call signal and the TV broadcasting signal, it creates a problem in designing a low-priced and small-sized radio terminal.
FIG. 2 is a view illustrating another antenna structure of a conventional TV phone for receiving an audio call signal and a TV broadcasting signal. According to the antenna structure of FIG. 2, a general antenna ANT is used for transmitting and receiving of the CDMA audio signal and receiving the TV broadcast signal. Specifically, the antenna ANT of the TV phone 10 is connected to the phone duplexer 14, and to the TV tuner 12 through band pass filter 16. The band pass filter 16 filters and outputs to the TV tuner 12 the TV broadcasting frequency received through the antenna ANT. Though using a conventional CDMA phone antenna for receiving the TV broadcasting signal may reduce the problem in designing a low-priced radio terminal, the receiving sensitivity of the TV broadcasting signal is compromised since the construction of the antenna is designed for receiving the CDMA audio signal
Accordingly, the present invention solves the problems inherent in the related art, and an object of the present invention is to provide an apparatus for commonly using a single antenna for an audio call signal and a TV broadcasting signal in a radio communication terminal TV phone which improves the receiving sensitivity of both the TV broadcasting signal and the call signal at a low cost.
It is another object of the present invention to provide an apparatus for commonly using an antenna for a call signal and a TV broadcasting signal in a radio communication terminal which improves the receiving sensitivity of both the TV broadcasting signal and the call signal with its construction simplified and small-sized.
In order to achieve the above objects, according to the present invention, there is provided an apparatus for commonly using an antenna for a call signal and a TV broadcasting signal in a radio communication terminal having an antenna, a phone duplexer, and a TV tuner, the apparatus comprising an LC parallel circuit connected between the antenna and the phone duplexer for forming an LC resonance circuit for a call signal frequency band, an LC series circuit connected to a connection point of the LC parallel circuit and the antenna and to a DC power supply terminal, a stub for TV broadcast signal impedance matching one terminal of which is connected between a capacitor and an inductor of the LC series circuit and the other terminal which is connected to the TV tuner, and a path providing section for providing a path between a connected point of the stub and the TV tuner and a ground terminal in accordance with a switching control signal provided according to a TV or call operating mode.